A conventional diaphragm valve typically has a valve housing including a valve seat and a bonnet, a handwheel, a flexible diaphragm made of an elastomeric material, a compressor, and a stem. The flow rate of a fluid passing through the valve housing can be controlled by manually rotating the handwheel to adjust the position of the diaphragm relative to the valve seat.
A conventional diaphragm valve is typically positioned in a conduit of a system for controlling fluid flow through the conduit. One problem that can be encountered with a conventional diaphragm valve is the tendency rotate the handwheel unduly while adjusting the valve into the closed position, which may result in excessive compressive forces on the diaphragm. This may damage the surface of the diaphragm to the point where it has to be replaced. This repair work tends to be expensive, time consuming, and temporarily disrupts the operation of the system.